Please help: idles no throttle‏
1986 300SDL
W126.125
OM603.961

The issue is:
Engine idles, but has no throttle/acceleration response.

What has been done:

* NEW Fuel.
* NEW Fuel tank screen, no effect.
* NEW Fuel filters (spin on and transparent), no effect.
* NEW Plastic fuel lines between injection pump and filter housing, no effect.
* NEW Delivery valve seals and crush washers, no effect.
* NEW Shutoff valve, no effect.
* NEW Lift pump, no effect.
* NEW MONARK Injector nozzles (balanced + new heat shields).
* NEW fuses.
* NEW OVP fuse.
* All rubber hoses replaced, (including injector return lines + plug)..
* Swapped fuel supply and return hoses, no effect.
* Ran directly off diesel purge bottle, no effect...
* Plugged fuel return line, no effect.
* Bypassed fuel thermostat.
* Disconnected exhaust system from turbo, no effect.
* Checked turbo, spins free, no slop.

NO trap oxidizer on this car...

Here is the link to OVP diagnostic data you asked for.


OVP relay, Over Voltage Protection Links
OVP relay, Over Voltage Protection Links

Welcome to the forum.

Can you elaborate on the above?

If you open the rack at idle...........what happens?

Can you drive it at all.........?? If so, can you get a 0-60 time?


It would be inconceivable that the engine won't increase rpm's in neutral................

If by rack you mean the throttle linkage no nothing! The car starts and idles fine (it idles at about 650) and no matter if I push pedal or lift linkage under hood RPM's go up about 100 (to 750) then it falls on it's face no matter how much throttle I give it. I ran it with out the intake crossover on, without the intake on, with out the turbo air intake elbow on (To see if turbo was spinning, it was) So I am getting fuel, air, compression (405psi-410 across all cylinders) and exhaust is flowing so I'm not restricted there what else does a diesel engine need to run electrcity and sensors so thats the new agenda. I have no 0-60 (really I don't) all I got is start it up put it in gear and let off the brake! So I got maybe 2-3 MPH no matter what throttle input is so car (Jada) hasn't left the driveway in about three weeks while Roy and I try everything "in the book" we're grasping at straws and have figured at least 100 things it isn't so now on to OVP's and speed sensors and electronics ect.

If by rack you mean the throttle linkage no nothing!
The car starts and idles fine (it idles at about 650) and no matter if I push pedal or lift linkage under hood RPM's go up about 100 (to 750) then it falls on it's face no matter how much throttle I give it.
I ran it without the intake crossover on, without the intake on, without the turbo air intake elbow on (To see if turbo was spinning, it was).
So I am getting fuel, air, compression (405-410 psi across all cylinders) and exhaust is flowing so I'm not restricted there, what else does a diesel engine need to run electricity and sensors so thats the new agenda.
I have no 0-60 (really I don't) all I got is start it up put it in gear and let off the brake! So I got maybe 2-3 MPH no matter what throttle input is so car (Jada) hasn't left the driveway in about three weeks while Roy and I try everything "in the book" we're grasping at straws and have figured at least 100 things it isn't so now on to OVP's and speed sensors and electronics etc.

Hello Noah

Could you please describe the moment this issue started.

Tweaked to remove odd software format.



NOTE:
Engine vacuum pump supply is 22...

I would be suspicious of the vacuum connections. If you remove ALL the vacuum lines from the IP it should start and run fine, unless the governor inside the IP broke a spring or something.

It should shift pretty firmly, but if they truly are banging, that's another vacuum system trouble. If the shop is not familiar with these systems, they'll probably just make it worse. There are plenty of posts that describe the adjustments necessary to the Vacuum Control Valve, the operation of the amplifiers, Bowden cable, etc.

__________________
James Marriott
2003 Buick Regal
1983 300D (228k, frau Auto)
1996 Suburban K2500 (192k, 6.5 turbo diesel/4WD towmaster 10,000)
www.engineeringworks.biz
1987 300SDL junker 170k
1982 300SD junker, 265k

It's strictly a mechanical control of the IP. No vacuum or electrical controls will affect the outcome.

Find the lever on the injection pump that controls the rack. See if the linkage from the pedal to the rack is intact (which it probably isn't).

If the IP lever is moving properly throughout its range (which is highly unlikely), then the IP is toast (which is also highly unlikely).

This plastic block or terminal that OVP plugs into has it's holes numbered
1 is top right (#30 pin on OVP plugs into it)
3 is blow that and is blank
5 is bottom right (# 31 pin on OVP)
2 is top left (#87 pin on OVP)
4 is middle left (#87 pin on OVP)
6 is bottom left (#15 pin on OVP)

With the key OFF!!

#1 gets full battery voltage in this case 12.43
#2 gets .01
#3 is blank
#4,5,6 all have 0 volts

With key ON!!

#1 gets full battery volts 12.08
#2 gets .02 volts
#3 blank
#4 gets 1.18 volts
#5 0 volts but the negetive sign on the left of mutimeter screen shows up (might be nothing but thought I would mention it)
#6 has full battery volts 12.08

My pedal is fine the rod that goes through the fire wall and up is fine
the part bolted to the intake is fine
the linkage moves or cycles to and from the cruise control accuator
it moves the lever on the injection pump and has the return spring intact
so all my linkage is moving

When it is idleing and I give it full throttle it kinda boggs down and rightfully so in my opinion it got more diesel than it can burn because RPM's aren't there to burn it
I get bogged down if I have too much food in my belly!

Incorrect my dear Watson.

It cannot get more diesel than it can burn unless it's under load. In that case, black smoke will be pouring out the back.

At idle, more fuel will simply cause it to increase rpm's. If you give it too much fuel, it will run up against the maximum governor speed.

Your belly is not a diesel engine...........

Just a thought,
While its idling try spraying some WD40 or diesel into the inlet of the turbo. It should increase rpm. If it does then maybe there is a problem with the internal connections in your IP. If the rpm does not increase, it should blow black smoke.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Well this is thought provoking. You might try starting the car with the air filter canister open. Inject a quantity of wd 40 at a rate that seems to meet the engines needs. See if rpms pick up.

At least that would eliminate some things. You have to divide things now to get at the real issue.

It does look like the injection pump yet you have to prove it somehow. I do not think the mechanical advance timing unit is defective as it would still pick up quite a bit but might be fairly sluggish.

This bogging down effect you are getting when you advance the linkage is interesting. The govenor may be trying to shut down the rack. The wd 40 or perhaps a better substitute spray test should indicate something.

I am not familiar with your 603 type engine. Doubt it is advanced or controlled enough by electrical/electronics sensors and devices etc to do what it is doing now. I was kind of under the impression right or wrong only the idle was regulated to some extent electrically/electronically.

If the engine picks up revs on the wd 40. I suspect the rack motion etc may be viewable through an inspection port on the injection pump. Others will have to quote if enough is viewable throught the inspection port to be worthwile looking at. It could be as simple as internally the pump arm is not transfering motion.

The rack feeds from the govenor I believe so what you see in a static situation unless the govenor is also viewable may not mean much. Again I am not knowledgeable enough to be totally certain about the sequence of events inside the injection pump that advances the rack. Others will know a lot more.

Well I just saw layback40 posted pretty much the same information when I was thinking and typing this response.